Replaceable circuit board mounting system in outer rotor motors

ABSTRACT

A circuit board containing control mechanisms for operation of an electric fan motor is fixedly assembled exteriorly to an end flange of the motor in only one position so that electrical contacts on the board extend through apertures in the end flange to cooperate with contacts on the motor side of the end flange to provide a completed motor. Assembly of the circuit board can be done without disassembly of the fan or motor, so that testing prior to insertion is possible.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to an electric motor having a flange disk that isarranged vertically to the motor shaft, and the stator being fixed tothe interior side of said flange disk, and having a control circuit forthe motor for which a circuit board is provided that is arrangedplane-parallel to the flange disk on the side of the stator that facesthe flange disk.

In the case of an electric motor of this type that is known from DE-AlNo. 25 14 067, the circuit board is developed to be ring-shaped and isarranged coaxially to the motor shaft between the stator and the flangedisk.

For the mass production of driving motors, an electric circuit isrequired that, as a rule, is manufactured at a separate manufacturingsite. Those manufacturers of electric motors who are not equipped formanufacturing circuits of this type, purchase these, together with thecircuit board, from the outside. Large-scale purchasers of electricmotors of this type are often manufacturers of electronic apparatuses.Under certain circumstances, these large-scale purchasers may be able tocost-effectively manufacture these circuits with the circuit boardsthemselves. This is particularly true if the electric motors in questionare part of a fan, for such fans are often used for the cooling inelectronic apparatuses.

For this reason, it is an objective of the invention to develop anelectric motor of the initially mentioned type in such a way that thecircuit board with the circuit can subsequently be convenientlyinstalled into the otherwise completely finished electric motor, for thepurpose of rationalizing the manufacturing process, in that, forexample, the manufacturer of electric motors furnishes the electricmotors to his customers without the circuit board, and the customer canthen manufacture the circuit boards rationally himself and can alsoinstall them subsequently in a convenient way.

An objective is achieved by the fact that the circuit board is arrangedon the exterior side of the flange disk that faces away from the stator.

For this purpose, the circuit board is preferably ring-shaped--possiblywith recesses at the exterior edge--and arranged coaxially to the motorshaft.

The invention makes it possible to prefabricate unfinished drivingmotors that are fully operable finished driving motors, except for thecircuit board that has to be inserted, and then subsequently, whenrequired, equip them with a circuit board and as a result finish themcompletely.

Circuit boards may be used that are equipped with different controlcircuits, according to the desired motor operation. In this case, onlyone single unfinished motor type must be held available for differenttypes of motors, which simplifies mass production and also warehousing.

The circuit boards may be glued in, clamped in, screwed in or fastenedin another way. It is advantageous to fasten the circuit board by meansof a locking means into which the circuit board can be easily inserted.On such a locking arrangement, a passageway is provided through thecircuit board and spring elements on the flange disk are compressedtogether and inserted through the passageway and then allowed to expandand catch onto recess areas on the circuit board, to hold the circuitboard to the flange disk. In this way, the subsequent mounting of thecircuit board is largely prepared and facilitated.

The connection of the stator to the circuit board may take place bysoldered or welded electrical connections. The required soldering andwelding operations are not necessary if the connection is established bymeans of contacts connected to the stator which automatically cooperatewith counter-contacts on the circuit board when the board is insertedinto the flange disk.

It is recommended to cover the circuit board on its back side facingaway from the flange disk by means of an insulating plate. Theinsulating plate may be a glued-on foil.

The circuit board is held securely and also protected with respect tomechanical outside effects if a recess is provided on the exterior sideof the flange disk, into which the circuit board fits. In this case, thefit can exist only in the case of a certain rotating position of thecircuit board and always ensure the same assembly situation.

It is desirable that the circuit board not protrude to the outside fromthe contour of the flange disk and thus not increase the axial length ofthe electric motor. This can be achieved by a correspondingly flatdevelopment of the circuit board and a deep development of theindentation.

Under certain circumstances, built-up circuit elements are used in thecontrol circuit. These are preferably arranged on the front side of thecircuit board that faces the flange disk, and if they do not find spacein the identation, they will find space in the provided recesses and/orbreakthroughs of the flange disk.

The magnetic field change-over in response to the revolution timing ofan electric motor, in the case of modern motors of the type that isconcerned here, preferably takes place by a contactless scanning of therespective rotational position of the rotor. A sensor element that isrequired for this purpose, for its function, must have a certainposition in proximity of the rotor.

The invention can preferably be used in motors that are equipped withthis type of sensor element, because, by means of the invention, it canbe ensured in a simple way that the sensor element, when the circuitboard is inserted, always takes up precisely the position that isindicated for its function. To that end, the sensor element is mountedto the circuit board at its exterior side and extends through anaperature therein toward the rotor so that when the circuit board ispositioned securely in its recess in the flange disk, the sensor isextended through the aperture adjacent the rotor. Since the circuitboard can only be located in one position on the flange disk, the sensoris always positioned accurately.

In such a case, the development as a collectorless direct-current motorhaving a permanent-magnetic external rotor is preferred.

The sensor element may be a Hall generator. Preferably this Hallgenerator will be combined with the pertaining amplifier to form onesingle, integrated control element. This type of Hall generator, whenthe circuit board is inserted, projects close to the rotor poles, whileleaving an air gap.

Advantageously, the circuit board can be inserted into the otherwisecompletely mounted unfinished motor in such a way that the unfinishedmotor, when the circuit board is inserted and connected and when, ifrequired, the insulating disk is placed on it, is finished and operable.In this way, the motor is prefabricated except for the circuit board andits connection. The subsequent completion by equipping with the circuitboard requires only minimal expenditures.

A preferred use of the invention is in connection with a fan driven by asmall electric motor, because fans of this type, in large numbers, areinstalled into eletronic and electrical apparatuses for the purpose ofcooling them. The manufacturers of these electrical apparatuses who buythese fans from the outside from other manufacturing specialists, arewell equipped for manufacturing electrical circuit boards and canparticularly utilize the capacity for later installing the circuit boardprovided by means of the invention. In this case the circumstance alsohas an effect that this circuit board must be connected to the circuitof the electronic apparatus, so that the connecting process for theconnection of the circuit board to the unfinished motor is compatiblewith manufacturing of the apparatuses.

Electric motors of the type that is concerned here, as a rule, aretested with respect to their operation. This type of test is alsodesirable for the unfinished motors, if these are furnished for beinglater equipped with the circuit board. A manufacturing process thatpermits this type of testing of the unfinished motors in a simple way isobtained by having the motor complete except for the circuit board sothat it can be tested and shipped. At the shipped to site, the circuitboard is added without disassembly of any of the motor portions torender a complete motor unit. Therefore full testing of the motor andpump can occur at the factory.

These and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in connection with the accompanying drawings which show, for thepurposes of illustration only, one embodment in accordance with thepresent invention, and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an electric motor;

FIG. 2 is a cross-sectional view of a circuit board that is insertedinto a flange disk;

FIG. 3 is a cutout III from FIG. 2;

FIG. 4 is a cutout IV from FIG. 1 for an embodiment that was modifiedwith respect to FIG. 1; and

FIG. 5 is a cross-sectional view of a fan.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like reference numerals are usedto designate like parts and more particularly to FIG. 1 where theelectric motor 1 that has a flange disk 2 that extends vertically andessentially coaxially with respect to the motor shaft 3. At the interiorside 4 of the flange disk, the stator 5 is fastened. For this purpose,the bearing tube 6, by means of screws 7, 8, is screwed to the flangedisk 2. The bearing pipe 6 is pressed into the bundle of plates 9. Oneof two provided stator coils has the reference number 10.

The electric motor 1 is an external rotor motor, the external rotor ofwhich has the reference number 11. The shaft 12 of the external rotor 11is rotatably disposed in the bearing pipe 6. The electric motor 1 is acollectorless direct-current motor, the external rotor 11 of which isequipped with a permanent magnet 13. A ring-shaped circuit board has thereference number 15 and, plane-parallel to the flange disk and coaxiallyto the motor shaft 3, is fitted into an indentation 16 on the exteriorside 17 of the flange disk 2. This circuit board 15 carries a controlcircuit for the motor which, in addition to other circuit elements 18,19, 20, includes a Hall generator 21 that as the sensor elementrecognizes the rotating position of the rotor 11. There is an air gap 27between the generator 21 and rotor 11, allowing the generator 21 toapproach the rotor poles of the rotor 11. The Hall generator 21 as wellas the control element 19 does not have sufficient space in theindentation 16 and for this reason, a breakthrough 22, 23 is provided inthe flange disk 2 through which the respective control element will thenprotrude.

The raised control elements are arranged on the front side 24 of thecircuit board 15 that faces the flange disk, and the circuit board isembedded so deeply in the indentation 16 that with none of its parts itprotrudes beyond the outer contour that is given by the back side 25 ofthe flange disk. The back side 25 of the flange disk is covered by aglued-on insulating disk 26 that extends generously beyond the circuitboard.

By means of soldered connections 28, 29, the control circuit iselectrically connected to the stator coil 10. Corresponding solderedconnections are also provided for the other stator coil that is notshown.

Current is supplied via the electric lines 30, 31 leading to the outsideand to the control circuit of the circuit board.

The circuit board 15 may also be inserted subsequently, together withthe control elements 18, 19, 20, 21, into the otherwise completedunfinished motor. By means of edge projections, such as the edgeprojection 35 at the flange disk and corresponding edge recesses at thecircuit board 15, it is ensured that the circuit board is alwaysinserted in the same indicated position in which the Hall generator 21takes up the position closely opposite the rotor poles of the rotor 11that is provided for its operation.

For the finishing of the unfinished motor, the circuit board is firstinserted, is then electrically connected by means of the solderedconnections 28, 29 and is finally covered by the insulating plate 26.

The circuit board 15 is fastened by means of gluing, but may also befastened by means of screwing or by means of locking elements, as willbe discussed further below for another embodiment.

The circuit board 40 of FIGS. 2 and 3 is equipped with control elements41, 42, 43, 44 that are part of the control circuit. These controlelements are raised and do not find space in the identation 45 on theback 46 of the flange disk 47. For this purpose, breakthroughs 56, 57,48 and recesses 50 are provided for these control elements.

The circuit board 40 fits into the indentation 45 only in one singlerotating position. This is secured by several locking elements which aredistributed on the surface of the circuit board. One of these lockingelements is visible in FIGS. 2 and 3 and has the number 55.

The locking element 55 is provided on the back side 46 of the flangedisk 47 and, when the circuit board is inserted, interacts with acorresponding counterlocking element 51 of the circuit board 40 andforms a locking means that in each case is spring-loaded and holds thecircuit board.

The locking element 55 consists of two locking hooks 53, 54 that are ina resilient relationship with respect to one another. The counterlockingelement 51 is a stepped receiving opening in the circuit board. Thelocking hooks 53, 54, against the spring force that is inherent to them,can be bent with respect to one another from the locking position shownin FIG. 3 so that the circuit board can be fitted on and also be removedagain.

In the case of the embodiment that was only partially shown in FIG. 4,stationarily arranged contact pins 60, 61 are provided for theconnection of the stator coil 64, the winding ends of the coil beingconnected to said contact pins 60, 61. The contact pins are disposed ina thickened end of an endplate 62 made of plastic that extends along oneface of the coil 64. These contact pins 60, 61, when the circuit board63 is inserted, fit into countercontacts 65, 66 developed as bushes thatare fastened at the circuit board 63 and connected to the controlcircuit of this circuit board. When the circuit board is inserted, thecontact pins 60, 61 find an electrically conducting contact with thecountercontacts 65, 66. Corresponding contact connections are alsoprovided for the other stator coil that is not shown. Otherwise, thisembodiment is developed to be identical with the embodiment shown inFIG. 1.

In FIG. 5, two square rectangular frames of equal size have thereference numbers 101 and 102 and are arranged at both ends of a pipesection 103 and narrowly surround said pipe section. On the intake sideof the pipe section, a flange disk 104 having four spokes is mounted atthe pipe section 103 coaxially with respect to the pipe section, onlyone spoke 105 of said spokes being visible in the drawing in sectionalview. The flange disk, with the spokes, extends at one end of the pipesection, but is still located inside the pipe section. The parts thathave been described up to now are made of metal.

At the flange disk, the driving motor 109 is located completely insidesaid pipe section and coaxially to it. The stator has the referencenumber 110, and the rotor has the number 111. The rotor surrounds thestator with a cup-shaped exterior part 112. On the outside of thisexterior part 112 of the rotor, fan vanes 115, 116 are mounted thatextend in the ring-shaped flow duct 118 recessed between the exteriorpart 112 of the rotor and the pipe section 103.

For the control and the power supply of the driving motor, an electricalcontrol circuit 119 is used that is mounted on a circuit board 120. Theraised control elements 121, 122, 123 are all arranged on the front sideof the circuit board that faces the flange disk. For these raisedcontrol elements, recessed are provided in the flange disk, namely, forcontrol element 123, the recess 125 and for the control elements 121,122, the breakthroughs 126, 127 so that these control elements will findroom. The overall size of the recesses is only such that they do notimpair the required stability of the flange disk. The circuit board isfitted into a rear indentation 129 of the flange disk and, on its back130, is flush with the back 131 of the flange disk. So that the circuitboard is installed in the correct angular orientation, it has at itscircumference an invisible notch, to which an invisible nose of theflange disk corresponds. The circuit board is held by its fit in theidentation 129 and by invisible locking hooks that correspond to thelocking hooks of FIG. 3.

An insulating plate 132 with an excess edge is glued onto the back 130of the circuit board.

For the outside power supply of the circuit and of the other parts ofthe driving motor, a current lead 133 is provided that originates fromthe circuit board, is embedded in a prepared groove of a spoke and endsat a current connection contact.

For the connection of the current lead 133 to the circuit board, for thepower supply of the stator coils and for the control of these coils,contacts are used that are provided at the circuit board andcountercontacts that are arranged at the flange disk 104, said contactsand countercontacts being opposite one another when the circuit board isinserted, being developed as soldering or welding contacts and beingconnected with one another by soldering or welding when the circuitboard is inserted. Lines lead from the countercontacts to the statorcoils.

The fan shown in FIG. 5 can be completely assembled except for thecircuit board. After this has happened, it is possible, for example, ata distant usage site, to subsequently install the circuit board with thecircuit. Nothing has to be removed for this purpose, and the otherwiseprefabricated fan can remain the way it is.

After the circuit board is inserted, it is held by locking elements. Nowthe contacts must still be connected with the pertaining countercontactsand then the insulating plate 132 can be glued on and the fan is fullyoperable.

It is also an advantage, in the case of the invention, that by means ofthe easy accessibility of the circuit board, the circuit board can beexchanged later if the control circuit cannot be used if the motor is tobe controlled by a different control circuit.

During manufacturing, the following process is recommended. First, anunfinished motor is used that, except for the inserted and connectedcircuit board, is a fully operable electric motor. Then this unfinishedmotor is connected to a testing circuit that corresponds to the controlcircuit of an assigned circuit board and is tested. Now the unfinishedmotor can be furnished to a customer who inserts an assigned circuitboard, connects it and, if necessary, covers it by an insulating plate.

While I have shown and described only one embodiment in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible to numerous changes and modifications asknown to one having ordinary skill in the art, and I therefore do notwish to be limited to the details shown and described herein, but intendto cover all such modifications as are encompassed by the scope of theappended claims.

I claim:
 1. An electric motor having a motor shaft and a flange diskthat is arranged at right angles to the motor shaft; a stator fixed toan interior side of said flange disk; a control circuit means for themotor for which an insertible circuit board means is provided andarranged in a plane, parallel to the flange disk on the exterior side ofthe flange disk that faces away from the stator, said control circuitmeans providing electrical connection with control elements on thecircuit board means which extend through the flange disk and cooperatewith cooperating elements of the motor located on the interior side ofthe flange disk.
 2. An electric motor according to claim 1, whereinlocking elements means are provided at the exterior side of the flangedisk that interact with corresponding counterlocking elements means ofthe circuit board means to form a spring-loaded locking means holdingthe circuit board means in position when inserted.
 3. An electric motoraccording to claim 1, wherein the electrical connection includes in partthat the stator is connected electrically to stationarily arrangedcontact pin means; and countercontact bush means are provided on thecircuit board means cooperating with said contact pin means to providesaid electrical connection with said contact means when the circuitboard means is inserted.
 4. An electric motor according to claim 1,wherein the circuit board means has a back side that faces away from theflange disk and is covered by an insulating plate.
 5. An electric motoraccording to claim 1, wherein the exterior side of the flange disk isprovided with an indentation into which spring hook means on the circuitboard means fit.
 6. An electric motor according to claim 1, whereinraised control elements are arranged on a front side of the circuitboard means facing the flange disk and at least one of recesses andbreakthroughs are provided in the flange disk for the raised controlelements.
 7. An electric motor according to claim 1, wherein the controlcircuit means has a sensor element that recognizes the rotating positionof a rotor; of the motor; said sensor element arranged on the front sideof the circuit board means and, when the circuit board is inserted,protruding through an assigned breakthrough provided in the flange disk,up to the rotor; and wherein the circuit board means can be insertedinto the flange disk in only one single position with respect to saidflange disk.
 8. An electric motor according to claim 7, wherein theelectric motor is a collectorless direct-current motor with a permanentmagnetic external rotor; and the sensor element, when the circuit boardmeans is inserted, projects close to the rotor poles while leaving anair gap.
 9. An electric motor according to claim 7, wherein the sensorelement has a Hall generator.
 10. An electric motor according to claim1, wherein power lead means are provided for the external power supplyof the control circuit means and other parts of the motor from thecircuit board means.
 11. An electric motor according to claim 1, whereinthe circuit board means can be inserted into an otherwise completelyassembled unfinished motor without disassembly of said otherwiseunfinished motor.
 12. An electric motor according to claim 1, whereinthe motor has an external rotor motor means to drive a fan; said fan isequipped with a pipe section and surrounds a flow duct on the interiorof which the motor is coaxially disposed; spokes means for fastening theflange disk at the pipe section with the flange disk at one end of thepipe section; and said rotor means having a ring of vanes that arefastened on the outside at the rotor and extend inside the pipe sectionin a ring-shaped recessed flow duct.
 13. An electric motor according toclaim 5, wherein raised control elements are arranged on a front side ofthe circuit board means facing the flange disk and at least one ofrecesses and breakthroughs are provided in the flange disk for theraised control elements.
 14. An electric motor according to claim 8,wherein the sensor element has a Hall generator.
 15. An electric motoraccording to claim 2, wherein the electrical connection includes in partthat the stator is connected electrically to stationarily arrangedcontact means; and countercontacts means cooperating with said contactmeans to cause an electrical connection with said contact means when thecircuit board means is inserted.
 16. An electric motor according toclaim 2, wherein the exterior side of the flange disk is provided withan indentation into which the circuit board means fits.
 17. An electricmotor according to claim 3, wherein the exterior side of the flange diskis provided with an indentation into which the circuit board means fits.18. An electric motor according to claim 4, wherein the exterior side ofthe flange disk is provided with an indentation into which the circuitboard means fits.
 19. An electric motor according to claim 15, whereinthe exterior side of the flange disk is provided with an indentationinto which the circuit board means fits.
 20. An electric motor accordingto claim 2, wherein raised control elements are arranged on a front sideof the circuit board means facing the flange disk and at least one ofrecesses and breakthroughs are provided in the flange disk for theraised control elements.
 21. An electric motor according to claim 3,wherein raised control elements are arranged on a front side of thecircuit board means facing the flange disk and at least one of recessesand breakthroughs are provided in the flange disk for the raised controlelements.
 22. An electric motor according to claim 4, wherein raisedcontrol elements are arranged on a front side of the circuit board meansfacing the flange disk and at least one of recesses and breakthroughsare provided in the flange disk for the raised control elements.
 23. Anelectric motor according to claim 19, wherein raised control elementsare arranged on a front side of the circuit board means facing theflange disk and at least one of recesses and breakthroughs are providedin the flange disk for the raised control elements.
 24. An electricmotor according to claim 15, wherein raised control elements arearranged on a front side of the circuit board means facing the flangedisk and at least one of recesses and breakthroughs are provided in theflange disk for the raised control elements.
 25. An electric motoraccording to claim 16, wherein raised control elements are arranged on afront side of the circuit board means facing the flange disk and atleast one of recesses and breakthroughs are provided in the flange diskfor the raised control elements.
 26. An electric motor according toclaim 17, wherein raised control elements are arranged on a front sideof the circuit board means facing the flange disk and at least one ofrecesses and breakthroughs are provided in the flange disk for theraised control elements.
 27. An electric motor according to claim 18,wherein raised control elements are arranged on a front side of thecircuit board means facing the flange disk and at least one of recessesand breakthroughs are provided in the flange disk for the raised controlelements.